CRP is a protein that is active in the form of pentameric CRP composed of five CRP monomers via noncovalent bonds. Most of CRPs are found as pentameric CRPs in vivo. In the present specification, CRP means pentameric CRP unless otherwise specified.
In the field of clinical study, CRP is one type of acute-phase protein that is increased due to acute inflammation or acute breakdown of tissue, and is known as a typical inflammation marker. The quantification of CRP is indispensable for observing the activities, severities, or courses of various diseases responsible for inflammation or tissue damage. Thus, CRP is routinely assayed in hospitals, clinical study centers, or the like. CRP assay kits used in this procedure often contain standard CRP solutions. Thus, CRP is consumed in large amounts every day. For such reasons, the production of highly pure and inexpensive CRP has been demanded.
Studies have been made on use of genetic engineering approaches for producing highly pure CRP. Only a genetic engineering method for producing CRP with E. coli as a host (Patent Literature 1) has been achieved commercially.